Most individuals buy and use a hair shampoo for its cleansing properties. A consumer often also desires a hair shampoo that imparts other desirable properties to the hair or scalp, such as conditioning, antidandruff and set retention properties. For example, consumers often desire sufficiently-conditioned hair that holds a preset configuration. However, hair shampoos generally are formulated with highly effective synthetic surfactants, like anionic surfactants, that primarily cleanse as opposed to conditioning the hair. Therefore, shampoos usually neither aid in the detangling of wet hair nor impart any residual conditioning benefits to dry hair, such as manageability or styleability of hair sets.
The hair normally is left in an unconditioned, cosmetically-unsatisfactory state after washing with an anionic surfactant-based hair shampoo, because anionic surfactants not only remove the dirt and soil from the hair, but also remove essentially all of the sebum naturally present on the surface of the hair fibers. Therefore, although anionic surfactants effectively cleanse the hair, the anionic surfactants also leave the hair in a cosmetically-unsatisfactory condition. In general, hair shampoo compositions containing anionic surfactants, or nonionic surfactants or amphoteric surfactants, leave the hair with an undesirable harsh, dull and dry touch, or feel, usually called "creak", after the hair is shampooed and then rinsed with water.
Thoroughly cleansed hair also is extremely difficult to comb, in either the wet or the dry state, because the individual hair fibers tend to snarl, kink and interlock with each other. In addition, incompletely dried hair, such as hair dried with towel, has poor brushing properties, and after complete drying, the hair does not set well. Furthermore, the combing or brushing property of the hair remains, poor, and the hair has undesirable electrostatic properties in a low humidity atmosphere that causes the hair to "fly away", thereby further reducing the brushing properties of the hair. The unsatisfactory combing or brushing property of hair immediately after shampooing, also causes hair damage, such as split ends or hair breakage. In addition, the natural luster and resiliency of the hair is reduced. Consequently, the overall unsatisfactory condition of the shampooed hair usually necessitates a subsequent post-shampoo treatment of the hair with a conditioning composition to improve these undesirable physical characteristics. These conditioning compositions normally are applied separately from the hair shampoo, and usually are rinses or cream-like lotions containing a cationic compound that is substantive to the hair.
Therefore, consumer needs traditionally have been met by the application of a shampoo to cleanse the hair, followed by the application of a conditioner composition to improve wet combing and other properties. The commonly accepted method has been to shampoo the hair, followed by rinsing the hair, and then separately applying a conditioner composition, followed by a second rinse. As previously discussed, freshly shampooed hair is inclined to knot and tangle, and therefore is difficult to comb and difficult to manage. The wet combing problem has been solved by treating shampooed hair with a conditioner composition that coats the hair shaft and causes the individual hair shafts in a tress to resist tangling and matting because of the conditioner residue retained on the shaft.
Consumers also often use an antidandruff shampoo. The incorporation of antidandruff agents into anionic surfactant-based hair shampoos is well known. The antidandruff agents not only must relieve the flaking and itching symptoms of dandruff, but also must be substantive to the skin and hair in order to extend the efficacy of the antidandruff agent from one shampoo treatment to the next. These properties are most often found in compounds that are insoluble in aqueous media, and this inherent insolubility of the antidandruff agent makes formulation of a stable, aqueous, anionic surfactant-based antidandruff shampoo a difficult problem.
In order to incorporate effective, water-insoluble antidandruff agents into an aqueous surfactant-based hair shampoo, one or more suspending agents are required to maintain the antidandruff agent homogeneously dispersed throughout the aqueous solution. Failure to adequately suspend the antidandruff agent leads to eventual shampoo separation as the antidandruff agent settles to the bottom of the container, and results in poor dandruff control and consumer complaints. As a result, investigators have continuously sought suitable suspending agents capable of effectively dispersing antidandruff agents, such as zinc pyrithione or sulfur, in aqueous media.
While numerous shampoos that include hair conditioners or antidandruff compounds have been disclosed, such shampoos have not been totally satisfactory for a variety of reasons. In regard to shampoo-conditioner compositions, one problem relates to compatibility problems between anionic cleansing surfactants and cationic compounds that are good conditioning agents. This compatibility problem has caused workers in the field to investigate other surfactants, such as nonionics, amphoterics and zwitterionics, as a total or partial replacement for the anionic cleansing surfactant. Many of these efforts are reflected in patents issued in the shampoo conditioner area. See for example U.S. Pat. No. 3,849,348 to Hewitt; U.S. Pat. No. 3,990,991 to Gerstein; and U.S. Pat. No. 3,822,312 to Sato. However, the nonionic, amphoteric and zwitterionic surfactants are inferior cleansing surfactants compared to the anionic surfactants.
Accordingly, to avoid the cationic-anionic incompatibility problem, to increase the degree of conditioning imparted to the hair and to maintain the cleansing efficiency of the hair shampoo, investigators incorporated silicone compounds into surfactant-based shampoo compositions. A problem inherent in formulating a silicone-based shampoo conditioner is the phase separation that results when a water-insoluble silicone conditioning agent is included in the aqueous shampoo-conditioner composition. Silicones included in shampoo-conditioner compositions have been disclosed in a number of different patents, including U.S. Pat. No. 2,826,551 to Green; U.S. Pat. No. 3,964,500 to Drakoff; U.S. Pat. No. 4,364,837 to Pader; British Pat. No. 849,433 to Woolston; U.S. Pat. No. 4,741,855 to Grote, et al.; U.S. Pat. Nos. 4,788,006 and 4,902,499 to Bolich, Jr. et al. and U.S. Pat. No. 4,704,272 to Oh et al.
A particularly difficult problem encountered in silicone-containing shampoo-conditioners is maintaining a dispersed, insoluble silicone material suspended in stable form, while retaining the cleansing and conditioning performance of the conditioning shampoo-conditioner product. A variety of materials have been proposed for inclusion in silicone-containing conditioning shampoos for purposes of thickening and stabilization such as xanthan gum, long chain acyl derivatives, long chain amide oxides, and long chain alkanolamides as disclosed in U.S. Pat. Nos. 4,788,006; 4,704,272; and 4,741,855.
In particular, Oh et al., in U.S. Pat. No. 4,704,272, disclose shampoo compositions including an anionic surfactant, a nonvolatile silicone, a hair conditioning agent and a suspending agent. The hair conditioning agent can be a tri-long chain (C.sub.8 -C.sub.22) amine, such as tri (isodecyl)amine or tri-C.sub.13 amine. Oh et al. also teach that a suspending agent, like a xanthan gum or a long chain acyl derivative, is essential to the composition. Surprisingly, it has been found that a primary, secondary or tertiary amine including at least one carbon chain having at least 16 carbon atoms, and neutralized with a suitable acid, provides a stable shampoo composition that effectively resists separation of the water-insoluble hair-treating compound from the shampoo composition without the need for a separate suspending agent.
Bolich et al., in U.S. Pat. No. 4,472,375, disclose an aqueous hair conditioning composition comprising a volatile hydrocarbon or a volatile silicone; a nonionic thickening agent; a quaternary ammonium salt and/or a salt of a fatty amine. The composition of Bolich et al. does not include an anionic cleansing surfactant and relies upon the nonionic thickening agent, e.g., a polymer, to suspend the water-insoluble ingredients. The present composition does not rely on a thickening agent to maintain phase stability of the composition.
A similar problem is encountered in regard to an antidandruff shampoo wherein a water-insoluble particulate antidandruff agent tends to separate from the aqueous hair shampoo base. Therefore, compositions containing insoluble particulate matter, like an antidandruff agent, require a suspending agent to assist in dispersing the particulate matter evenly throughout the composition. The suspending agent can be any one of a number of inorganic minerals or synthetic or natural polymers or gums. Among the most often used suspending agents are colloidal aluminum oxide, modified magnesium aluminum silicate, xanthan gum, fumed silica, algin products, polyacrylic acid, sodium carboxymethylcellulose, hydroxypropylcellulose, synthetic sodium magnesium silicate, colloidal attapulgite clay, lignins and alkanolamides. Any antidandruff agent and additional suspending agents added to a basic hair shampoo base should add antidandruff properties to the shampoo without detracting from the cleansing efficiency and esthetic appeal of the shampoo. Unfortunately, the antidandruff agents and necessary suspending agents often adversely affect the foaming characteristics of the shampoo composition.
Therefore, the need for improved stable compositions that condition the hair, i.e., render the hair more manageable, or that impart antidandruff properties, has long been recognized in the art. Consequently, the present invention is directed to stable hair shampoo compositions including a cleansing surfactant and a water-insoluble hair treating compound, like a silicone conditioner or an antidandruff agent, wherein the hair shampoo composition effectively resists phase separation because of the presence of a new suspending agent comprising an amine including at least one alkyl chain of sufficient chain length and a suitable acid.
As will be demonstrated more fully hereinafter, a hair shampoo composition, comprising a cleansing surfactant; a water-insoluble hair treating compound, like a silicone conditioning compound or an antidandruff agent; a suspending agent comprising a fatty amine having at least one alkyl group including at least about 16 carbon atoms or a fatty amidoamine having an alkyl group including at least about 13 carbon atoms and a suitable acid; and a suitable carrier, comprising water, effectively resists phase separation and effectively delivers the water-insoluble hair treating compound to the hair or scalp.